What the @#@$@ is Tunnel adapter Teredo Tunneling Pseudo-Interface??

This is what I get when I run IPCONFIG. It gives a strange IP address and includes sonething called "Tunnel adapter Teredo Tunneling Pseudo-Interface:" Does anyone know what this is? Should I get rid of it? How to get rid of it? Before I reformatted my drive this wasn't there. I have 2 comps connected thru a DLINK router and I can ping everything fine from SYSTEM1 but I can't ping from SYSTEM2 to SYSTEM1.

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